1 use crate::rustc_target::abi::LayoutOf as _;
3 use helpers::check_arg_count;
4 use rustc_ast::ast::Mutability;
5 use rustc_middle::ty::{self, TypeAndMut};
6 use rustc_span::BytePos;
7 use rustc_target::abi::Size;
8 use std::convert::TryInto as _;
10 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
11 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
12 fn handle_miri_get_backtrace(
14 args: &[OpTy<'tcx, Tag>],
15 dest: &PlaceTy<'tcx, Tag>,
16 ) -> InterpResult<'tcx> {
17 let this = self.eval_context_mut();
19 let &[ref flags] = check_arg_count(args)?;
21 let flags = this.read_scalar(flags)?.to_u64()?;
23 throw_unsup_format!("unknown `miri_get_backtrace` flags {}", flags);
26 let mut data = Vec::new();
27 for frame in this.active_thread_stack().iter().rev() {
28 let mut span = frame.current_span();
29 // Match the behavior of runtime backtrace spans
30 // by using a non-macro span in our backtrace. See `FunctionCx::debug_loc`.
31 if span.from_expansion() && !tcx.sess.opts.debugging_opts.debug_macros {
32 span = rustc_span::hygiene::walk_chain(span, frame.body.span.ctxt())
34 data.push((frame.instance, span.lo()));
37 let ptrs: Vec<_> = data
39 .map(|(instance, pos)| {
40 // We represent a frame pointer by using the `span.lo` value
41 // as an offset into the function's allocation. This gives us an
42 // opaque pointer that we can return to user code, and allows us
43 // to reconstruct the needed frame information in `handle_miri_resolve_frame`.
44 // Note that we never actually read or write anything from/to this pointer -
45 // all of the data is represented by the pointer value itself.
46 let mut fn_ptr = this.memory.create_fn_alloc(FnVal::Instance(instance));
47 fn_ptr.offset = Size::from_bytes(pos.0);
54 let ptr_ty = tcx.mk_ptr(TypeAndMut { ty: tcx.types.unit, mutbl: Mutability::Mut });
56 let array_ty = tcx.mk_array(ptr_ty, ptrs.len().try_into().unwrap());
58 // Write pointers into array
59 let alloc = this.allocate(this.layout_of(array_ty).unwrap(), MiriMemoryKind::Rust.into());
60 for (i, ptr) in ptrs.into_iter().enumerate() {
61 let place = this.mplace_index(&alloc, i as u64)?;
62 this.write_immediate_to_mplace(ptr.into(), &place)?;
66 Immediate::new_slice(alloc.ptr.into(), len.try_into().unwrap(), this),
72 fn handle_miri_resolve_frame(
74 args: &[OpTy<'tcx, Tag>],
75 dest: &PlaceTy<'tcx, Tag>,
76 ) -> InterpResult<'tcx> {
77 let this = self.eval_context_mut();
79 let &[ref ptr, ref flags] = check_arg_count(args)?;
81 let flags = this.read_scalar(flags)?.to_u64()?;
83 throw_unsup_format!("unknown `miri_resolve_frame` flags {}", flags);
86 let ptr = this.force_ptr(this.read_scalar(ptr)?.check_init()?)?;
88 let fn_instance = if let Some(GlobalAlloc::Function(instance)) =
89 this.tcx.get_global_alloc(ptr.alloc_id)
93 throw_ub_format!("expected function pointer, found {:?}", ptr);
96 // Reconstruct the original function pointer,
97 // which we pass to user code.
99 fn_ptr.offset = Size::from_bytes(0);
100 let fn_ptr = Scalar::Ptr(fn_ptr);
102 let num_fields = dest.layout.layout.fields.count();
104 if !(4..=5).contains(&num_fields) {
105 // Always mention 5 fields, since the 4-field struct
106 // is deprecated and slated for removal.
108 "bad declaration of miri_resolve_frame - should return a struct with 5 fields"
112 let pos = BytePos(ptr.offset.bytes().try_into().unwrap());
113 let name = fn_instance.to_string();
115 let lo = tcx.sess.source_map().lookup_char_pos(pos);
117 let filename = lo.file.name.prefer_remapped().to_string();
118 let lineno: u32 = lo.line as u32;
119 // `lo.col` is 0-based - add 1 to make it 1-based for the caller.
120 let colno: u32 = lo.col.0 as u32 + 1;
122 let name_alloc = this.allocate_str(&name, MiriMemoryKind::Rust.into());
123 let filename_alloc = this.allocate_str(&filename, MiriMemoryKind::Rust.into());
124 let lineno_alloc = Scalar::from_u32(lineno);
125 let colno_alloc = Scalar::from_u32(colno);
127 let dest = this.force_allocation(dest)?;
128 if let ty::Adt(adt, _) = dest.layout.ty.kind() {
131 "miri_resolve_frame must be declared with a `#[repr(C)]` return type"
136 this.write_immediate(name_alloc.to_ref(), &this.mplace_field(&dest, 0)?.into())?;
137 this.write_immediate(filename_alloc.to_ref(), &this.mplace_field(&dest, 1)?.into())?;
138 this.write_scalar(lineno_alloc, &this.mplace_field(&dest, 2)?.into())?;
139 this.write_scalar(colno_alloc, &this.mplace_field(&dest, 3)?.into())?;
141 // Support a 4-field struct for now - this is deprecated
142 // and slated for removal.
144 this.write_scalar(fn_ptr, &this.mplace_field(&dest, 4)?.into())?;